RocksdayPsilomelane vs Pyrolusite
The quickest way to tell Psilomelane from Pyrolusite: Psilomelane leaves a brown streak; Pyrolusite leaves black.
A group name for hard, black manganese oxides — including romanechite and hollandite — not a single mineral species.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Manganese dioxide, usually black and sooty; it leaves black marks on fingers.
Photo: Unknown authorUnknown author, Public domain
Quick tests
- Streak (rub on unglazed porcelain): Psilomelane leaves a brown streak; Pyrolusite leaves black.
- Luster: Pyrolusite looks metallic; Psilomelane doesn't.
Key differences
- Pyrolusite is softer and leaves black dust on your fingers.
Side by side
| Property | Psilomelane | Pyrolusite |
|---|---|---|
| Type | Mineraloid | Mineral |
| Mohs hardness | 5–6 | 2–6.5 |
| Luster | Submetallic to dull | Metallic to earthy |
| Streak | Brown | Black |
| Colors | Black, Gray | Black, Gray |
| Crystal system / structure | Botryoidal mixture of manganese oxides | Tetragonal |
| Specific gravity | 3.7–4.7 | 4.4–5.1 |
| Formula | — | MnO₂ |
| Found in | Romanèche, France; Arizona | Germany; Brazil |
Properties that are the same for both are grayed out.
How to identify psilomelane
- Black, often grape-like (botryoidal) or massive.
- Brownish-black streak.
- Harder than pyrolusite: a knife may barely scratch it.
Structure: Botryoidal mixture of manganese oxides
Full Psilomelane guide →How to identify pyrolusite
- Sooty black masses that dirty your fingers.
- Black streak.
- Fern-like black 'dendrites' on rock surfaces.
Crystal system: Tetragonal
Full Pyrolusite guide →More comparisons
Frequently asked questions
What is the difference between psilomelane and pyrolusite?
Psilomelane is a mineraloid with a Mohs hardness of 5–6 and a submetallic to dull luster, usually black or gray. Pyrolusite is a mineral (MnO₂) with a Mohs hardness of 2–6.5 and a metallic to earthy luster, usually black or gray.
How can you tell psilomelane from pyrolusite?
Psilomelane leaves a brown streak; Pyrolusite leaves black. Pyrolusite looks metallic; Psilomelane doesn't. Pyrolusite is softer and leaves black dust on your fingers.
Could you tell them apart from a blurry close-up?
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